Thermal printer

Abstract

A thermal printer according to one embodiment includes a thermal head, a temperature sensor, and a control unit. The thermal head includes a plurality of heating elements. The temperature sensor is provided in the thermal head and is configured to measure a temperature of the thermal head. The control unit is configured to control an amount of heat generated from the heating elements by determining a pulse supply time for which a pulse signal is supplied to the thermal head based on the temperature of the thermal head and a cumulative heat generation time of the thermal head.

What is claimed is: 
     
       1. A thermal printer, comprising:
 a thermal head including a plurality of heating elements; 
 a temperature sensor configured to measure a temperature of the thermal head, the temperature sensor being provided in the thermal head; and 
 a controller configured to control an amount of heat generated from the plurality of heating elements by determining a pulse supply time for which a pulse signal is supplied to the thermal head based on the temperature of the thermal head measured by the temperature sensor and a cumulative heat generation time of the thermal head, 
 wherein when a printing operation is not executed, the controller subtracts the cumulative heat generation time per predetermined period of time. 
 
     
     
       2. The thermal printer according to  claim 1 , wherein when the cumulative heat generation time is longer than or equal to a predetermined threshold, the controller decreases the pulse supply time to be shorter than a time determined based on the temperature of the thermal head. 
     
     
       3. The thermal printer according to  claim 2 , further comprising:
 a storage component configured to store a table showing a relationship between the temperature of the thermal head and the pulse supply time, wherein when the cumulative heat generation time is longer than or equal to a predetermined threshold, the controller adjusts a reference source of the table to be on a side higher than the temperature of the thermal head. 
 
     
     
       4. The thermal printer according to  claim 3 , wherein the table is a heat generation time table, the heat generation time table indicates as the temperature of the thermal head increases, the pulse supply time decreases. 
     
     
       5. The thermal printer according to  claim 1 , wherein the controller adds a time to the cumulative heat generation time, the time being obtained by multiplying a proportion of heating elements used for printing among the heating elements by the pulse supply time. 
     
     
       6. The thermal printer according to  claim 1 , wherein the plurality of heating elements are arranged in a straight line. 
     
     
       7. The thermal printer according to  claim 1 , wherein the temperature sensor comprises a thermistor. 
     
     
       8. A method for a thermal printer, comprising:
 supplying a pulse signal to a thermal head including a plurality of heating elements; 
 measuring a temperature of a thermal head; and 
 controlling an amount of heat generated from the plurality of heating elements by determining a pulse supply time for which the pulse signal is supplied to the thermal head based on the temperature of the thermal head measured and a cumulative heat generation time of the thermal head, wherein when a printing operation is not executed, subtracting the cumulative heat generation time per predetermined period of time. 
 
     
     
       9. The method according to  claim 8 , further comprising:
 when the cumulative heat generation time is longer than or equal to a predetermined threshold, decreasing the pulse supply time to be shorter than a time determined based on the temperature of the thermal head. 
 
     
     
       10. The method according to  claim 9 , further comprising:
 storing a table showing a relationship between the temperature of the thermal head and the pulse supply time; and 
 when the cumulative heat generation time is longer than or equal to a predetermined threshold, adjusting a reference source of the table to be on a side higher than the temperature of the thermal head. 
 
     
     
       11. A POS terminal, comprising:
 a roll paper holder; 
 a plurality of rollers; 
 a discharge port; and 
 a thermal printer, comprising:
 a thermal head including a plurality of heating elements; 
 a temperature sensor configured to measure a temperature of the thermal head, the temperature sensor being provided in the thermal head; and 
 a controller configured to control an amount of heat generated from the plurality of heating elements by determining a pulse supply time for which a pulse signal is supplied to the thermal head based on the temperature of the thermal head measured by the temperature sensor and a cumulative heat generation time of the thermal head, wherein when a printing operation is not executed, the controller subtracts the cumulative heat generation time per predetermined period of time. 
 
 
     
     
       12. The POS terminal according to  claim 11 , wherein when the cumulative heat generation time is longer than or equal to a predetermined threshold, the controller decreases the pulse supply time to be shorter than a time determined based on the temperature of the thermal head. 
     
     
       13. The POS terminal according to  claim 12 , further comprising:
 a storage component configured to store a table showing a relationship between the temperature of the thermal head and the pulse supply time, wherein when the cumulative heat generation time is longer than or equal to a predetermined threshold, the controller adjusts a reference source of the table to be on a side higher than the temperature of the thermal head. 
 
     
     
       14. The POS terminal according to  claim 13 , wherein the table is a heat generation time table, the heat generation time table indicates as the temperature of the thermal head increases, the pulse supply time decreases. 
     
     
       15. The POS terminal according to  claim 11 , wherein the controller adds a time to the cumulative heat generation time, the time being obtained by multiplying a proportion of heating elements used for printing among the heating elements by the pulse supply time. 
     
     
       16. The POS terminal according to  claim 11 , wherein the plurality of heating elements are arranged in a straight line. 
     
     
       17. The POS terminal according to  claim 11 , wherein the temperature sensor comprises a thermistor.